Mine support with resilient release means



Nov. 5, 1968 1.. R. BOWER 3,408,820

MINE SUPPORT WITH RESILIENT RELEASE MEANS Filed Aug. 17, 1966 5 Sheets-Sheet l F| 3 INVENTOR LEW/8 ROBERT BOWER BY Z Q :;g

, ATTORNEY Nov. 5, 1968 R. BOWER 3,408,820

MINE SUPPORT WITH RESILIENT RELEASE MEANS Filed Aug. 17, 1966 5 Sheets-Sheet 2 INVENTOR LEW/S ROBERT BOWE'R BY ATTORNEY Nov. 5, 1968 1.. R. BOWER 3,408,820

MINE SUPPORT WITH RESILIENT RELEASE MEANS Filed Aug. 17, 1966 5 Sheets-Sheet IS INVENTOR LEW/S ROBERT BOWER K/ ATTORNEY 3,408,820 l MINE SUPPORT WITH RESILIENT i RELEASE MEANS Lewis R. Bower, Hillstown, near Chesterfield, Derby, England, assignor to A. G. Wild & Co. Limited, Sheffield, Yorkshire, England, a British company 1 Filed Aug. '17, 1966; Ser. No. 573,084

Y 7 Claims. (Cl. 6145) I The aim of theinvention is to assist the positive and speedy loweringof the hydraulic supports'or chocks when they are retracted from the roof.

With the foregoing aim in view and in-accordance with the invention we provide a fluid-operated mine roof support comprising a'roof bar'supported by at least two chocks including sp'ring' means associated with the roof bar and arrangedto be deformed when the support is set to the roof, the construction being such-'that the energy so stored in the sprung means is utilised to assist in lowering the chocks when the pressure internally thereof is released. I

Illustrative embodiments of the invention will now be particularly described with reference to the accompanying drawings, in which: I

FIGS. 1 and 2 are diagrammatic side elevations of 'a first embodiment of roof support according to the invention;

FIG. 3 is a front elevation of the support shown in FIGS. 1 and 2;

FIGS. 4 and 5 are diagrammatic side elevations of another embodiment of roof support according to the invention;

FIG. 6 is a front elevation of the support shown in FIGS. 4 and 5;

FIG. 7 is a diagrammatic side elevation of a further embodiment of roof support according to the invention;

FIGS. 8 and 9 are front elevation views of the roof support shown in FIG. 7 showing the retracted (from the roof) extended conditions respectively.

In one embodiment of the invention the roof support is of the kind above referred to as being used in longwall mining, the support in this embodiment comprising two hydraulic chocks 1 disposed one behind the other and supporting a roof bar 2 and a cantilever extension 3 thereof. Each chock is surmounted by a rocker support 4 on which the roof bar 3 is mounted. A pivot pin 5 passes through apertures in the walls of the roof bar and each rocker support, the ends of each pin projecting beyond the side walls of the roof bar as seen in FIG. 3. Two steel springs 6 constituting spring means are mounted on the projecting ends of the two pivot pins 5 so as to extend respectively, one on each side of the roof bar, over the space between the two chocks of the unit. The springs are of arcuate curvature, the convex surfaces being uppermost and projecting above the top of the roof bar so as, when the chock is set to the roof, to bear against the roof before the roof bar comes into contact ice ' of elongated eyelets as seen in FIG. 2. They "are spaced from the sides of the roof bar by short spacer tubes '7 and washers carried on the pivot pin 5 on the inner sides" of the springs and are retained on the pin by washers 8 and split pins 9 on the outer sides of the springs,

It. will be appreciated that with the arrangement described the action of setting the roof support to the roof will increase the radius of each Spring resulting in deflecting the springs by an amount corresponding to the pre-set above the roof bar. This deflection induces in the spring a loading which is stored in the spring until the roof support is lowered from the roof. This loading of the spring sets up reactions at the hinge points both in the vertical and horizontal planes. If the horizontal reactions were restricted by the hinge points theywould tend to spread the chock centres. This is undesirable and it is for this reason that the eyelets at the ends of the springs are elongated in order to eliminate the horizontal reactions. When the roof members are to be lowered from the roof the chock cylinders are connected to exhaust and, the above mentioned horizontal reactions having been eliminated, the remaining vertical reactions act downwardly to push the unit away from the roof by.an amount corresponding to the preset of the springs.

The elongated eyelets at the ends of the springs could be replaced by circular eyelets. In this modification the spring mounting would be slotted. in order to eliminate the horizontal reactions above referred to. s

In another modification of the above embodiment, not illustrated, instead of forming the ends of the springs with eyes or eyelets the ends of the springs are plain, i.e. not shaped, and are located in box like shoes secured to the sides of the roof bar. The shoes are rectangular in cross-section, the tops of the shoes being partly open at one end to permit the insertion thereinto of the ends of the springs, these ends being free to slide in the shoes longitudinally of the roof bar. y

It is to be understood that the spring arrangement in the embodiment above described can be varied in a number of ways. For example four springs could be used,

with considerably smaller spans, mounted in pairs centrally over each chock. In general the number and size of the springs used would be decided by the prevailing roof conditions and the lowering characteristics desired.

In another embodiment of the invention, illustrated in FIGS. 4 to 6, the top surface of the roof bar is formed with a recess 20 extending substantially over the space between the two chocks of the support unit. A single spring of convex curvature is mounted in this recess with its convex surface uppermost, the ends of the spring being retained in the recess by keep plates 10 fixed to the top of the roof bar and overlapping the recess so as to form pockets at the ends of the recess. When the chocks are retracted from the roof the ends of the spring are spaced from the end walls of the recess, as seen in FIG. 4, the convex surface of the spring projecting above the top of the roof bar. The action of the spring is exactly the same as in the embodiment first described, but in this FIGS. 4 to 6 embodiment the horizontal reactions are eliminated because the ends of the spring are free to spread outwardly in the pockets beneath the keep plates. These keep plates facilitate assembly of the spring.

In this embodiment more than one spring may be provided, the number and size of the springs being as in the first embodiment decided by the prevailing roof conditions and the lowering characteristics required.

In the various embodiments above described the spring or springs extend parallel with the roof bar. This is not always necessary to the invention and the spring or springs may be mounted so as to extend transversely of the roof bar, i.e. approximately parallel to the coal face.

Patented Nov. 5, 1968 2 l 1}." 3 r In another embodiment incorporating this modified construction two springs are mounted on the roof bar respectively adjacent to but 'not aligned with the two chocks. This embodiment is illustrated in FIGS. 7 to 9. The ends of 'each' spring are rolled over into circular shape as seen in FIGS. 8 and 9 and are engaged by pins 13 passing through elongated slots in pairs of mounting plates 12 or lugs projecting laterally from opposite sides of the roof bar 2, the pins being retained between washers 8 and split pins 9 mounted on the ends of the pins 14 which project beyond the lugs and split pins. The springs 6 are of arcuate shape, the convex surfaces being uppermost and projecting above the roof bar to provide the required amount'of pre-set. The action of the springs in this embodiment is similar to that of the spring or springs in the first and second embodiments. When the support is set to the roof the horizontal 1 reactions are eliminated because the pins passing through the ends of the springs are free to slide outwardly in the elongated slots. This embodiment cansbe modified in various'ways. For example the elongated slots in the mounting plates could be replaced by circular eyelets, the circular eyelets at the ends of the springs being replaced by elongated eyelets. Further shorter springs could be installed in a recess similar to that provided in the second embodiment.

It is also possible to integrate the arrangements of any two of the embodiments described, so that a plurality of springs are arranged in a cruciform manner.

It is to be understood that the power required to push down the checks will depend upon the severity of the difiiculties above referred to, but the power available can be controlled in the design of the spring or springs, by the selection of the span of the spring, the amount of pre-set and/ or by constructing the spring or springs with one or more leaves. However, if for a given power requirement roof condition were predominantly soft then it would be advisable to use a wide spring, or wide springs, rather than narrow ones, in order to ensure that the springs do deflect and not become embedded in the roof. Thus, the number and size of the springs used would depend on the prevailing roof conditions and the lowering characteristic desired and the maximum advantage and efliciency will be obtained by giving full consideration to these variables.

It is further to be understood that a spring arrangement according to the invention can be easily adapted for use under the base members of a roof support unit to obtain the same advantages.

We s a V V.

1. A fluid operated mine roof support comprising:

(a) at least two fluid operated chocks spaced laterally from each other;

(b) a rigid roof bar extending between and movably connected tothe uppe'rends of said chocks, the upper surface of js aid roof bar, adapted to contact and support a mine, roof: a

(c) at least one -bowed leaf springhaving its-ends slidably mounted on said roof-barswithits bowed central" portion normally-"projecting above the upper surface of said roof bar and'adapted to be deformed and flattened and store energy when the roof bar is applied to the mine roof by extension of the fluid operatedchocks and to utilize said stored energy to assist in moving the cross bar out of contact with the mine'roof when the fluid chocks are contracted.

'2. A mine roof support as defined" in claim 1 in which the leaf spring extends generally parallel to saidroof bar. 3. A mine roof support as defined in claim 1 in which the leaf spring extends transverse to said' roof bar.

4. A mine roof support as defined in claim 1 in which the ends of the-leaf spring are provided with eyes receiv= ing pins which serve to attach the spring to the roof bar.

5. A mine roof support as defined in claim 4 in which the eyes receiving the pins are elongated to permit lateral movement of the eyes with respect to the pins.

6. A mine root support as defined in claim 4 in which the pins attaching the spring to the roof bar are mounted in elongated slots in the roof bar to permit longitudinal movement of the spring ends in the roof bar.

7. A mine roof support as defined in claim 1 in which the root bar has a recess in theupper surface thereof receiving each spring, and keep plates covering the ends of the recess and the ends of the spring to retain the spring therein.

. References Cited UNITED STATES PATENTS 3,333,809 8/1967 Bower 248--357 FOREIGN PATENTS 1,002,184 3/ 1952 France.

865,922 4/ 1961 Great Britain.

ROY D. FRAZIER, Primary Examiner.

J. FRANKLIN FOSS, Assistant Examiner. 

